Laser microdissection systems are used for extracting selected microscopic objects from biological specimens using a laser beam produced by a laser. The material (the collected microdissected pieces) extracted in sufficient quantities is subsequently supplied to further biochemical analysis steps. At present, laser microdissection systems are predominantly used in the medico-biological field.
A laser microdissection method and a laser microdissection system of this kind are described, for example, in German Patents No. DE 100 43 506 C1 and DE 100 18 251 C2. Such a laser microdissection system is made up of a plurality of precisely mutually synchronized components. The central component is a microscope which has many motorized functions and which includes an electronically adjustable x-y stage for accommodating the specimen to be processed. The laser beam produced in a laser unit is coupled via an optical system having integrated beam deflection into the beam path of the microscope and is deflected by the microscope objective onto different locations of the fixed specimen in order to cut the same. In another embodiment, the laser beam is held immovably, and the specimen is moved by the x-y stage relative thereto. All of the control functions are executed by a suitably designed program which runs on a connected computer. The image detail of the specimen that is visible in the microscope is displayed on the computer monitor by a camera that is adapted to the microscope. Using the computer mouse, the user can draw a boundary line, referred to in the following as a nominal cutting line, around selected specimen regions, enclosing the same. Every line drawn in this manner is characterized by a series of x-y point coordinates which are defined relative to the monitor coordinates. Upon activation of the cutting command, the laser beam is controlled by a suitable x-y mapping system in such a way that the previously defined drawing line is imaged onto the specimen, so that a true-to-scale, affine mapping of the monitor line is scanned on the specimen. Thus, the objects that had been manually marked beforehand are cut out by the properly adjusted laser beam. As described in German Patent No. DE 100 18 251 C2, the system allows the microdissected pieces to be selectively collected for further processing in a standardized small collection vessel underneath the cutting plane, a plurality of collection vessels being selectable and automatically movable to the collecting position.
However, the inherent drawback of the known laser microdissection method is that the process of marking the objects to be cut out, as undertaken by the user, is complex, time-consuming, and error-prone. This holds true in particular when a relatively large number of microdissected pieces is required for the subsequent analysis steps. In this case, fatigue and other influences affecting the user can have serious consequences.